This invention relates to fluid-type mattresses such as water bed mattresses and air mattresses and, more particularly, to fluid-damping and shape-defining inserts for use with such mattresses.
The construction of fluid-type mattresses from fluid impervious, flexible, thermoplastic sheeting, such as polyvinyl chloride sheeting having a thickness of at least about 20 mils, is well known in the prior art.
The prior art has also recognized the need for inserts to assist in maintaining the configuration of fluid-type mattresses by modulating fluid flow and limiting geometrical distortion during ordinary use of such mattresses.
Such inserts, which are generally constructed from the same or similar flexible material as that employed for the boundary sheets of the mattress, are secured, in opposing locations, to the inner surface of the upper and lower boundary sheets of the mattress. The inserts are loaded in tension upon the application of internal fluid pressure and, by extending across the fluid volume, impede the movement of fluid within the mattress.
The prior art as illustrated by U.S. Pat. No. 4,172,301 (Everard et al., 1979) and U.S. Pat. No. 4,167,432 (Mollura, 1979) as well as pages 82, 83, Industry Magazine, American National, September 1978, discloses that vertically apertured, flexible, cylindrical-type coils can be disposed within fluid-type mattresses and connected to the top and bottom sheets thereof for restricting wave motion and preventing the top boundary sheet of the mattress from rising. In such construction, the forces acting on the inserts are transmitted to relatively small regions in the mattress boundary sheet. A major disadvantage of this construction lies in the sensitivity to overload of the connection between the insert and the boundary sheet. As a result of repeated application of forces through ordinary use and momentary overload, failure can occur at such connection which renders the mattress unserviceable through breach of the fluid-impervious mattress sheet.
It is, therefore, an object of this invention to provide flow-damping and shape-defining inserts for fluid-type mattresses, such as water-bed mattresses, wherein the attachments of such inserts to the oppositely disposed, mattress boundary sheets are through extended-length seams.
Another object of this invention is to provide a fluid-type mattress insert comprising flexible damping means and oppositely disposed, flexible, enlarged flange means wherein the damping means are secured to the flange means by first seams and the flange means are secured to the oppositely disposed mattress sheets by second seams having greater peripheral length and strength than the first seams whereby forces acting on the insert will be accommodated by flexure or, in the limit, by failure at or about the first seam, leaving the mattress boundary sheets unimpaired.